Dolphins sometimes have fun by blowing bubbles and creating rings of air underwater, which they then swim through.
17
Parrotfish make themselves a kind of mucus 'sleeping bag' which masks their smell from predators and keeps parasites away.
4
Cats sleep for 70% of their lives.
8
Some lizards, in which the tail is a major storage organ for accumulating reserves, will return to a dropped tail after the threat has passed, and will eat it to recover part of the sacrificed supplies.
13